During the oxidation of the alcohol of vegetable solutions, some of the other organic matters present also suffer change. A white gelatinous mass (_mother of vinegar_)[5] is commonly deposited; but this is a secondary result of the process, and not, as formerly supposed, one essential to it. In ordinary cases acetification occurs only at or near the surface of the liquid; which accounts for the length of time required for the operation under the old process of ‘fielding,’ and the shorter time in which it is accomplished by the improved process of Mr Ham. It proceeds favorably at temperatures ranging from 60° to 90° Fahr.; and most rapidly at 95° Fahr. (Liebig). In the ‘quick process’ of making vinegar a temperature of 90° to 92° is generally aimed at; but it often rises to 100°, or even to 105°, Fahr. As the temperature falls acetification proceeds more slowly, and at 46 to 50° Fahr. it ceases altogether (Liebig). [Footnote 5: It has generally been asserted that this substance contains vibriones, and other low forms of organised life; but Mulder describes it, under the name _mycoderma aceti_, as a plant of the order ‘fungi.’ It is formed at the expense of the constituents of the vinegar, and often causes whole vats of it to pass into water.] Aldehyd (see _above_) is an exceedingly volatile substance, and easily dissipated by a slight heat. It is, therefore, of the highest importance to duly regulate the temperature, as well as the supply of air, during acetification. In the ‘quick process’ of making vinegar the loss from this cause is always considerable, and often very great. This loss may be diminished by passing the heated air, as it escapes from the acetifier, through a porcelain or silvered copper worm or refrigerator, set in a chamber containing water of a temperature not higher than 40° to 45° Fahr.; the connection being made at the _lower_ end of the worm, whilst the upper end is open to the air. On the small scale, as in the platinum-black process, the loss may be almost entirely prevented by causing the upper air tube to pass through a vessel containing ice or a freezing mixture; or by uniting it with the lower end of a Liebig’s condenser. In liquors undergoing the vinous fermentation, a portion of the newly formed alcohol is invariably acetified whenever the temperature rises above 51° Fahr.; and at a higher temperature, this proceeds with a rapidity often highly injurious to the quality of the liquor. In this way there is frequently a useless loss of the alcohol, which is rendered more apparent by the incipient, and sometimes the actual, souring of the liquor. =ACETIM′ETRY=. _Syn._ ACETOM′ETRY; ACÉTOMÉTRIE, Fr.; ACETIME′TRIA, &c., L. The art or process of determining the quantity of pure acetic acid in vinegar, or in any other liquid. The plans generally adopted for this purpose are—— I. From the saturating power of the acid, as in the common methods of acidimetry:——